WPAD Configuration - weird behaviour

Hello Community,

we have a Sophos UTM SG330 Appliance running on version: 9.508

In the section: "Web Protection-> Filtering Options -> Misc" we use the following proxy auto configuration:

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function FindProxyForURL(url, host) {
var resolved_ip = dnsResolve(host);
//Don't proxy connections to the UTM web interface
if (shExpMatch(url, "proxy.xxx.local:4444/*")) return "DIRECT";
//Exclude non-fqdn hosts from being proxied
if (isPlainHostName(host)) return "DIRECT";
//Don't proxy Connections to Legacy NGA Net
if ((shExpMatch(url, "^http://194.150.1.*")) ||
(shExpMatch(url,"^https://194.150.1.*"))) return "DIRECT";
if ((shExpMatch(url, "^http://194.150.0.*")) ||
(shExpMatch(url,"^https://194.150.0.*"))) return "DIRECT";
if (shExpMatch(url, "mobile.xxx.net")) return "PROXY 10.46.0.34:8080";

//Don't proxy connections to the exempted URL matches
if (shExpMatch(url, "xxx.net")) return "DIRECT";
if (shExpMatch(host, "citrix.xxx.net")) return "DIRECT";
if (shExpMatch(host, "owa.xxx.net")) return "DIRECT";
if (shExpMatch(host, "autodiscover.xxx.net")) return "DIRECT";
if (shExpMatch(host, "autodiscover.xxx.ch")) return "DIRECT";
if (shExpMatch(host, "viewer.xxx.net")) return "DIRECT";
if (shExpMatch(host, "transfer.xxx.net")) return "DIRECT";
if (shExpMatch(host, "hotspot.xxx.net")) return "DIRECT";
if (shExpMatch(host, "remote.xxx.net")) return "DIRECT";
if (shExpMatch(host, "meeting.xxx.net")) return "DIRECT";
if (shExpMatch(host, "outlook.xxx.local")) return "DIRECT";
if (shExpMatch(host, "*.xxx.local/*")) return "DIRECT";
if (shExpMatch(host, "xxx.local")) return "DIRECT";
//Don't proxy connections to private IP addresses
if (isPlainHostName(host) ||
shExpMatch(host, "*.local") ||
isInNet(resolved_ip, "10.0.0.0", "255.0.0.0") ||
isInNet(resolved_ip, "172.16.0.0", "255.240.0.0") ||
isInNet(resolved_ip, "192.168.0.0", "255.255.0.0") ||
isInNet(resolved_ip, "127.0.0.0", "255.255.255.0") ||
isInNet(resolved_ip, "xxx.xx.xxx.xxx", "255.255.255.255"))
return "DIRECT";
return "PROXY 10.46.0.34:8080";
}

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Now we have sometimes a weired behaviour on the client pcs while accessing some websites.

For example:

1. Proxy- Configuration in Internet Explorer:  Just ticked the checkbox: Automatic detect proxy settings 

Then if we navigate to: https://www.icloud.com it isn't possible to access the website. 

Thats why we have an exception defined in: "Web Protection -> Filtering Options":

But the access is still not possible.

Now if we change the proxy settings in Internet Explorer to this:

All is working good. 

Can one explain this?

Thanks so far!